Impact nut runner



De@ i2, 1950 G. c. wlLl-nDE Erm. 2,533,703

IMPACT NUT RUNNER 5 sheets-sheet 1 Filed June 21; 1947 lrlh'ffi* ik 2 JNVENToRs.

I I 32 auw/v c. Mul/oe F I #M1/wm 22%@ i o 2 j 5y, dfic/ r fg AT'OJE/VEYS Dec. 12, 1950 G. c.w|LH1DE ETAL IMPACT NUT RUNNER 5 Sheets-Sheet 2 Filed June 21, 1947 MMA Wwe law #L Ww m By FRANK L. Houma A TTOBNEYS Dec. l2, 1950 G. c. wml-:Inni: ErAL 2,533,703

11mm' NUT RUNNER Filed June 21. 1947 5 Sheets-Sheet 3 By AeA/w L. Hou-'ono jj, c 422451/ A TTORNEYS Del 12 1950 G. c. wlLHlnE ETAL 2,533,703

rumor nur RUNNER Filed June 21. 1947 5 Sheets-Sheet 4 :y Fen/wr .mumea jb s@ A TTGQNYS Dec. 12, 1950 G. c. w|LH|DE :TAL 2,533,703

nlPAcT NUT RUNNER Filed June 21. 1947 5 sheets-sheet 5` INVEN'roR. amv/v c. maf/o6 www Nasa/v BA/nse 'By FRAN/f L. Hou-'090 `A Trae/Veys out a work day.

v n 1 i Fig. l" is an elevational yview of an electrically Patented Dec. 12, 1950 IMPACT NUT RUNNER Glenn C. Wilhide, James N. Baker, and Frank L.

Halford, Towson, Md., assignors to The Black t Decker Manufacturing Company, Towson, Md., a corporation of Maryland AppiicationJune 21, 1947, Serial No. 758,114

13 Claims.

This invention relates to power operated portable tools of the general type commonly in use for running nuts and bolts into or out of assembly and to hammer mechanisms for cinching or loosening bolts, nuts, etc.

The general object is to provide a clutch and hammer mechanism which will be durable and accurate in torque eiort throughout long periods of use and yet be suiiiciently low in overall weight sa to not cause undubfatiguefwhen used through- More specifically, our invention is concerned with the provision of a novel hammer mechanism which can be associated with the usual yieldable tooth clutch mechanisms characteristic of portable nut runner tools and in such manner as not to be involved mechanically in that part of the transmission mechanism of the tool which exerts the normal torque egortnpon the wrench or :u f2s/ A further object is the provision of a power driven portable nut runner incorporating a hammer mechanism in such manner that a rebound build up of the impact forces can be accomplished without introducing additional problems other than the ultimate emcient functioning of the parts comprising the hammer mechanism.

Another object is the provision of a nut runner mechanism of the inertia hammer type wherein the force of the hammer blows may be transmitted directly to the socket or wrench mechanism thereby to avoid the transmitting of the hammer blows through the tooth and cam portions of the clutch mechanism.y

Other objects and advantages oi the invention will be apparent trom the following detailed descriptionv-,ofrpreferred Vforms .of embodiment or reference-being'madeto the acdrawings wherein:

driven portable nut runner incorporating the teatures of our invention;

Fig. 2 is an assembled elevation of the hammer, clutch and socket mechanism;

Fig. 3 is a cross-sectional view taken along the line 3 3 of Fig. 1:

Fig. 4 is a cross-sectional view taken along the line 4-4 of Fig. 1:

Fig. 5 is a cross-sectional view taken along the linej-B of Fig. 1;

Fig. 6 is a cross-sectional view taken along the line l-i o! Fig. 1;

Fig. 7 is a perspective view of the socket driving means compromising a driven clutch means (Cl. M12-30.5)

2V n hammer impact shoulders during normal driving of the socket wrench member;

Fig. 10 is a diagrammatic linear and angular representation of the clutch teeth and hammer impact shoulders during the camming period of the clutch teeth and while hammer spring is being tensioned; l

Fig. 11 is a diagrammatic linear and an angular representation ofthe clutch teeth and hammer impact shoulders, but showing the impact shoulders shifted to escape position upon complete driving disengagement of the clutch teeth but before the hammer has been accelerated by the torsion spring; and

Fig. 12 is a diagrammatic linear and an angular representation of the clutch teeth and impact shoulders at the time of impact.

Portable nut runners have been produced heretofore provided with some form or other of hammer means for delivering a series of blows to the wrench socket member after the nut, bolt, etc. has become seated. In some, this action has been obtained by having the clutch teeth on the driving clutch member rotatively pound upon the clutch teeth of the driven clutch member, the latter comprising an integral part of, or being directly connected to, the socket member. This rapid engaging and disengaging of the clutch teeth under such impact conditions caused deterioration of the clutch members to such an extent as to require frequent replacement. Cther types of tools incorporated energy storing means in the i'orm of distortable rubber torsion members or springs which comprised part of the torque transmitting means from motor to socket wrench or reactive auxiliary cam and clutch t means, allof which resulted in mechanical compromises with;

resulting laokfot durability and el'iiciency.

In our present invention the well known tooth lcam type of clutch mechanism is used for normal transmission and delivery of torque eiiort to the wrench or socket member up to a predetermined amount and the clutch maintaining spring has no other purpose or function than to maintain the clutch teeth engaged up to such predetermined torque efiort after the nut or bolt becomes seated and partly cinched, but gives way before the nut or bolt is cinched home. We propose to utilize a rotating hammer arrangement which will be actuated by energy stored in a second spring arrangement and this storing of energy is accomplished during interruption of the rotative movement of the hammer by -a continuously rotating drive shaft. A camming period immediately follows the seating of the nut or bolt with consequent arresting of the rotating movement of the socket or wrench member and the timed angular representation oi the clutch teeth and uo action or the hammer is such that under dynamic 3 conditions a torsion pendulum build up L1 obtained.

The hammer spring is inthe form of a torsion member connected at one end to the drive shaft of the tool and to the hammer at the other end. thus forming a flexible connection between Athe hammer and the shaft., The hammer is carried by the driving clutch member in an independently revoivable manner but is fixed axially on this clutch member thereby to be shiftable` axially with this clutch member. The torsion spring comprises no part of the means transmitting torque eort through the clutch member to the socket member, thus prolonging the life of the clutch members. A further advantage is that the clutch maintaining spring is burdened with no other function than to main tain the clutch and camming teeth in socket driving engagement up to a predetermined torque eifort upon the socket member and accordingly can be designed accurately to perform this single function.

Referring to the drawings, in Figs. l and 2 we show a portable, electrically-driven nut runner tool embodying the features of our invention.

The tool casing comprises a housing structure forming a motor housing member 20, a handle 22 mounted thereon having a switch mechanism 23 associated therewith for convenient starting and stopping of the motor 24. The upper end of the motor housing is formed to be closed as shown in Fig. 1, to support a bearing 2| attached to the top end of the motor shaft.

A. reduction gearmechanism is provided and gear, supporting frame structures 25 and 24 are secured respectively to the lower end of the motorY housing and to each other. The frame member 25 supports a motor shaft bearing 26 which supports the lower end 21 of the motor shaft. The second frame structure 24 affords bearing mountings for reduction gearing.

A fourth housing member 3l, in the form of a. cylinder having a converging bottom is secured to the framel member-.28v and supports a bearing member 3l. The bearing member 3l serves to support an anvil member or wrench turning means 32 against the thrust of a clutch closing spring 60, as will be described.

The motor shaft 21 has a pinion formation 21a on the lower end thereof and meshing with an intermediate gear 29, preferably integrally formedwith a pinion 34. The pinion 34 drives a large reduction gear 35 carried on a stud shaft 36. The stud shaft 36 is supported by bearings 31 and 38, these bearing members being supported by the frame members 25 and 28, respectively.

The mechanism arrangement so far described is to be found in nut runner tools heretofore manufactured and sold and generally is designed for the delivery of rated torque effort to be exerted upon a socket, nut orbolt and the like, through a yieldable cam tooth type clutch mechanism maintained normally closed by the spring 60. A clutch driving shaft 40 is supported independently of the gear reduction mechanism,

surface of member 4|. Member 42 is supported by a bearing mechanism 4S, and thebearing mechanism 4I is supported by the frame member 28. It will be seen that shaft 4I thus is power connected to the motor 24 and shaft 44 will be constantly driven so long as the motor is energized. The lower end 4l* of shaft 4l extends into a bore formed in the socket driving member l2 to provide a bearing for supporting the lower end of shaft 4l. The upper portion of shaft 4I has secured thereto an annularly flanged spring seating and spring anchoring member 3l which thrusts against small collar 34* seated in a groove formed in the splined part of shaft 44.

Spline connected to the intermediate part of shaft 44 is a clutch member I0, there being three sets of bearing balls M riding in keyways spaced apart and formed in the shaft 4I and clutch member. IQ so that the clutch member $4 able along shaft 4l.

` 1y mounted upon the driving clutch memberfll is a cylindrical inertia or hammer member 52, held rotatively upon clutch member I4 by bearingfballs il which roll in external and 'internal groves formed respectively in the outer face of the clutch "member 8l and the bore face of hammer member `i2whe)reby revolvable displacement between clutch membe'rand hammer member can take place, but the twommembers will remain relatively axially flied. e The lower end surface of clutch member il has two clutch teeth 50* o f the clutch and cam type spaced apart which engage two comiplementary clutch teeth 32* formed on the upper face of the socket wrench driving means or anvil member 32. Thesepairs of clutch teeth have the respective clutching surfaces thereof slopedor inclined to provide clutchopening or camming surfacesl A second spring in the form of paiydfnnfenigj." ergy storing means comprises a il coiledstrucg' ture l0 wound to extend outside of tlie connues"- sion spring it. The .upper end of spring terminates in 'agloop secured to a li formedfon the iiangedthrust member ,30. -g lower end of the spring terminates in a loop iat-- tached to alug formation 12 formed on .the ham'- mer member 52. It has'b'eenound in practice that having the spring endsloosely'connected'to the` hammer and to .the flanged thrust member I9 will minimizerupt'iiring off spring ends. A totalplay of the two; spring ach'orages of about four to seven degrees assures free movement-of the hammer. The arrangement of the mecha'- nism is such that this spring member is in anormally unloaded condition other than the effort required to rotate the hammer mass, but is designed to have a suillcient torsional strength to store predetermined amounts of energy when vstressed by either a spring winding or'unwind'ing exertion upon the ends of the spring. Hence, whenever relative, angular displacement of the ends II-J2 is brought about, energy is stored is shut'- l The compressed spring 4l is of pre'- determined compressipn to maintain the clutch e torsion will take place during a faces of these shoulders are disposed in a plane displaced about five degrees from a vertical plane. l

and the shoulders of each pair are spaced -l80 apart.

To prevent the hammer shoulders from rebounding or escaping from properly poised relation to the impact shoulders on the wrench driving member 32 and to tizegclutch teeth of clutch member 50. a radially extending lug 52 is formed on the top end of the hammer 52 to span about 120. The center line of this lug is approximately coincident with the center line of the hammer shoulders 52by and the hammer shoulders extend over an arc of about 50. A cooperating lug 50 isformed on the top of clutch member 50 to extend into the path of the hammer lug. The lug 50 spans an arc of labout 120 and normally is disposed approximately radially opposite lug 52. Lug 50 has its center line displaced about 90"` from the center line of clutch teeth 50. Thus relative-revolving movement between the hammer andthe clutch member 50 is limited to a distance of not more than 60 in either direction from a normal nut running position.

To a better understanding of the sequential actions which take place between the camming and clutchteeth and between the impact shoulders of the socket or driven clutch member 32 and the shoulders 52b on the hammer, several diagrams have been included in the drawings. They show the positions during normal nut runing; the positions at the time the nut has been seated and the clutch teeth are camming the clutch member 50 and hammer 52 upwardly, i. e., axially relative to shaft 40; and the positions at the instant of escapement of the clutch teeth and hammer shoulders and the positions at the time of impact. In these diagrams the direction of rotation of shaft 40 is assumed to be clockwise and the diagrams have been arranged by way of both linear and annu'lar demonstrations. It is important there to understand that the effective operating heightsy of both setsv of clutch teeth and the impact shoulders are shown in the di agrams as being equal, although in practice the effective height of the clutch teeth is one thirtysecond of an inch higher, for reasons stated later.

In Fig. 9 (normal nut running, that is,y with the rotation of the wrench member 32 unarrested) thehammer shoulders are shown in rotative alignment but out of contact with impact shoulders 32b of socket driving member 32, but thecamming faces of the clutch teeth 50 and 32 are being maintained in normal driving contact by spring 50. yUnder this condition torsion spring l is unloaded.

In Fig. 1`0 the nut has been seated and rotation of the socket driving member has been arrested by the seating of the nut. The cam teeth of clutch member 50 have been rotated relative to the cam teeth on member 32 a distance greater than they gap normally existing between the im- 6 pact shoulders of the the result that clutchmember 50 has been ,revolved relative to the arrested hammer, thus slightly stressing the torsion spring 10. 'I'he camaction of the clutch teeth in axially separating the impact shoulders and the clutch member hasprogressed beyond the relationship shown in Fig. 9.

In Fig. 11 the shoulders and clutch teeth have.

been shifted apart by the continued action of the camming faces of the clutch teeth to the point of instant escapement of the impact shoulders and the clutch teeth, and some energy has been stored in the torsion spring 10. The spring 10 is now free to actuate the hammer. The design of the spring 10 is such as to greatly acceler-f ate the revolving movement of the hammer in the direction of rotation of the shaft 40 and its clutch member 50.

l In Fig. 12 the position of the clutch teeth and shoulders is shown at the time of the impact or blow delivery to the socket driving member 32. Spring 60 has snapped the clutch member 50 and hammer 52 downwardly as viewed in Fig.

l, but the impact shoulders 52b of the hammer have struck the shoulders 32b of the socket driving member before the camming faces of the clutch teeth of the clutch member 50 have again been revolved into driving engagement with the camming faces of the socket driving member 32.

Then follows a rebound of the hammer shoulders relative to the anvil shoulders as shown in Fig. 9. It will be seen that at no time can the hammer be caused by spring 10 to overrun the clutch member 50. by reason of the /interacting stop.

shoulders 50 and 52 on the clutch member-50 and hammer member 52, respectively. Also it will be understood that the design of the torsionspring 10 and the weight of the hammer will be such as to deliver the desired amount ofblow to the socket driving member within the time interval indicated by the foregoing diagrammatic explanation-of actions, it being understood that spring design and hammer weight may vary in accordance with the size and capacity of the portable tool contemplated. In the instant de.

sign, for example, the contemplated speed .of the clutch shaft 40 is between 1200 to 1500 R. P M. and the torsion spring 10 is wound left-handed. Thus in a clockwise drive of shaft I0, the energy storingaction on 4the spring 'I0 comprises a tendency to wind up the spring, although it has been found that a right-hand wound spring will give the desired action even though there would be present an unwinding tendency.l

The actions set forth in'the diagrams are on the basis of a slow motion analysis and there is approximately a 15 spacing between anvil and stood by considering the upper end of the torsional spring to be stationary. The torsion spring 10 and hammer 50 then become a torsional pen.- dulum with respect to the rotating spindle as a base, and follow the harmonic laws of a torsional pendulum with respect to the spindle. The hammer shoulders 52", during extremely high resistance to rotation. become practically stationary but with respect to the spindle as a base possess' two clutch members with:

asas-,vos

a high speed of rotation relative to the spindle.4

Thus the slight winding of the torsion spring takes place at a high rotative speed equal to the relative speed of the hammer shoulders to the spindle. Therefore, relative to the spindle the harmonic cycle of the torsional pendulum starts with a velocity displacement from normal, and y,the inertia of the hammer will swing ythe torback through the normal to displacement with a speed equal to the velocity of displacement from vzero, or with a speed equal to the actual spindle speed superposed upon the velocity of the spindle whichserves as the reference base. Since the velocity of displacement is relative to the spindle as a base and is equal to the spindle speed itself, the absolute velocity of the return of the hammer through neutral is equal to twice the fixed spindle speed.

Just after returning through the neutral position with respect to the spindle and at a speed equal to the original velocity of displacement, the hammer shoulders 52 strike the anvil shoulders 32l This dynamic blow results in a rather high coefficient of restitution from the driven system manifest in a hammer rebound at considerable velocity relative to the stationary shoulders 32. During this recoil of the hammer shoulders, the displacement of the pendulum with respect to the spindle at' impact is seen to be made at a much higher relative velocity, which' is the sum of the rebound velocity relative to shoulder or anvil 32, plus the relative velocity of the shoulders 32 to the spindle. Consequently, if torsion spring surges are disregarded the hammer returns from larger displacements at greater velocity and tends to acquire a still higher rebound velocity.

Such a rebound build up will become uniform when the velocity of the hammer at impact is equal to the sum of the relative spindle .speed plus the product of the impacting velocity of the hammer and its coefficient of rebound velocity.

Should it be assumed that Fig. 9 portrays a dynamic condition with the lift cams beginning to open .instead of the slow motion explanation hereinbefore given, the hammer shoulders are rebound rotating, i. e., counter-clockwise at a high velocity of rebound, probably at a higher rotational speed than that of the cams rotating in the opposite direction. The energy of this velocity will be quickly absorbed by the torsion spring. It has been determined that the hammer lugs rebound through a substantial angle very rapidly and the hammer then dwells in a suspended condition while the rotation of the drive shaft continues to wind up the spring coils until the inertia of the suspended hammer is overcome whereupon hammer' rotation again takes place. While reference herein has been made to the torsion spring as an energy storing means it will be apparent to those skilled in the art that the energy of the mass spring system under dynamic condition of operation is composed of the kinetic and potential energy in the spring and the kinetic energy of the rotated hammer. The importance of the presence of the stop shoulders or lugs 52 and on the hammer and driving clutch member respectively during a condition of extreme 4dynamic cyclical build up become apparent for the oscillatory motion of the hammer otherwise could increase to the point where the action of the lift cams could be completed before the hammer should normally have recovered from rebound,

We have determined also that it is advisable to have the effective height of the clutch teem exceed the effective heights of the slightly sloping impact faces of the hammer shoulders so that the thrusting action of the clutch spring Il will be taken by the wrench or anvil member 32 and thus prevent pounding on the spline balls I3 for the spline grooves should be of sufiicient length to prevent impact on the balls I3. Thus the clutch closing action of spring 33 terminates by having the clutch teeth lands or top faces in contact with the valley faces thereof. Wrench member 32 transmits this thrust to the radial flange of bearing member 3|. Friction between the surfacesof the hammer and anvil is reduced to a minimum. The present tool is adaptable for both screwing and unscrewing bolts, nuts, etc.,

fthan the usual ratchet effect, is not transmittedI to the socket driving means through the clutchV mechanism which drives that means. Accordingly, the clutch mechanism and spring 33 can be designed in a practical and accurate way to perform the clutch and cam functions intended for delivery of a predetermined low torque effort at the socket. l

Accordingly the hammer mechanism can be designed wlthout the distractions of considerations involved in the designing and manufacturing of clutch mechanisms which would have to withstand the shock of hammer impacts at the rate of several thousand per minute.

We claim:

l. In a tool of the character described, the combination of a casing a driving and a driven clutch member having cam declutching teeth. a spring reacting on the casing for yieldingly maintaining the members engaged against the camming action of the teeth during a normal nut running operation, a hammer revolvablymounted upon the driving clutch member and having an impact shoulder adapted to strike an impact shoulder on the driven clutch member, a drive shaft surrounded by the spring and spline connected to the hammer carrying clutch member, the last mentioned clutch member being movable on the drive shaft to move the hammer axially of said shaft, means for'limiting relative revolving movement between the hammer and its clutch member, and a torsion' member connecting the shaft and hammer witli the said impact shoulders normally circumferentially spaced apart, the declutching camming action being such that relative rotation between the shaft `and the hammer effects accumulation of rebound energy in the torsion member during the separating actions of the clutch teeth and while the hammer is being shifted by the camming action axially relative to the shaft.

2. In aportable nut runner tool, two separable tooth clutch members one of which comprises a wrench turning means, a spring yieldingly maintaining the two clutch members in driving-driven relation during a' normal nut running operation, the teeth of the clutch members also comprising a camming means for effecting separation of the two clutch members against the inuence of said spring when the spring rating is exceeded by the camming forces. a cylindrical hammer mem.

ber revolvably mounted upon one of the clutch members to have a revolving movement relative to that member, stop means operatively disposed between the hammer member and the last mentioned clutch member for limiting said relative revolving movement to less than 180, a drive shaft drivingly splined to said last mentioned clutch memsber while permitting axial movement of that clutch member, an energy storing spring connected to the `hammer member and to the shaft. andA cooperating impact shoulders arranged on one end of the hammer member and on the wrench turning means clutch member and serving to effect rebound storing of energy in the energy storing member during camming apart actions of the clutch members and as an impact means upon closing of the clutch members.

3. In a portable electrically driven nutrunner tool, the combination of a power driven shaft, a wrench turning means having impact shoulders thereon, a pair of clutch members having clutch opening camming teeth for connecting the shaft to the wrench turning means, one of the clutch members comprising cams integral with. the wrench turning means, the other of the clutch members being spline connected to and shiftable axially of the shaft, a spring acting on the shiftable clutch member to maintain the clutch members in driving relation until the shaft exerts a predetermined maximum torque effort on the wrench turning means, a hammer member revolvably mounted on the shiftable clutch member and being in the form of a cylindrical inertia member having impact shoulders engageable with said shoulders on the wrench turning means, and a normally unloaded torsion spring connected to the hammer member and the shaft and adapted to store energy by reason of relaf tive rebound movement between shaft and hammer subsequent to an escapement movement between the clutch members.

4. In a portable electrically driven nut runner tool. the combination of a power driven shaft, a wrench turning means into which the shaft extends, a pair of clutch members of the camming tooth type for connecting the shaft to the wrench turning means, one of the clutch members comprising part of the wrench turning means and the other clutch member being spline connected to and shiftable axially of the shaft,

said clutch members comprising camming clutch teeth, a 'precompressed spring surrounding the shaft and acting on the shiftable `clutch member to maintain the clutch mechanism closed against the camming action of the clutch teeth while the shaft exerts a predetermined torque effort on the wrench turning means through the 4clutch mechanism, an impact member revolvably mounted on the shiftable clutch member and being in the form of a cylindrical inertia means having impact relation intermittently with the wrench turning means upon escapement of the clutch members, and a torsion spring connected to the cylinder and to the shaft and adapted to store energy by reason of relative rebound movement between shaft and cylinder subsequent to an escapement movement between the clutch members.

5. In a nut runner, a drive shaft, a wrench turning means, a revolvable hammer, said hammer and wrench turning means having cooperating impact shoulders, a torsion spring interconnecting the shaft and hammer for actuating the hammer, cam means for causing relative move. nient between the hammer and wrench turning means to move said shoulders into and out of alignment with one another during rotation of said shaft, said hammer being revolvable to oscillate independently of said cam means, and co operating stops on said hammer and cam means for limiting the degree of oscillation of the 'hammer relative to the cam means.

6. In a nut runner, a drive shaft, a wrench turning means, a revolvable hammer, said Chammer and wrench turning means having cooperating impact shoulders, torsion storing means interconnecting the shaft and hammer for actuating the hammer, a cam member revolvably supporting the hammer for causing movement of the hammer relative to the wrench turning means to move said shoulders into and out of alignment with one another during rotation of said shaft, said hammer being revolvable to oscillate independently of said cam member, and stops on said hammer and cam member for limiting the degree of oscillation of the hammer relative to the cam member.

7. In a nut runner, a drive shaft, a wrench turning means, a clutch member driven by the shaft and a clutch member drivingly connected with the wrench turning means, said members having cooperating cam faces and resilient means biasing the carn faces in engagement with one another for effecting transmission of torque through the members, one of said members being intermittently cammed from and toward the other axially of the shaft when the members rotate relative to one another, a hammer revolvably mounted on said axially cammed clutch member and moved axially thereby, said Chammer and wrench turning means having alignabie impact shoulders, and a torsion spring interconnecting the shaft and hammer for actuating the hammer, said impactshoulders being aligned but separated while said clutch members are in torque driving relation and being intermittently moved into and out of alignment during said intermittent moving of said axially shiftable the clutch members being in the form of an anvil member supported by the casing and the other clutch member being loosely splined to the shaft for axial movement along the shaft, a compression spring on the shaft yieldingly maintaining the members engaged against the camming action of the clutch teeth, a hammer revolvably mounted upon the splined clutch member and having an impact shoulder adapted to strike an impact shoulder on the anvil clutch member and a torsion spring connecting the shaft and hammer with the said impact shoulders angularly spaced out of contact, the declutching camming action being such that relative rotation between one of the clutch members and the hammer to accumulate energy in the torsion member by a rebound build up in successive cycles is effected subsequent to me separating actions of the teeth of the clutch members.

9. In a nut runner, a casing, a wrench turning means rotatably supported by the casing, a drive shaft rotatably supported within the casing', said wrench turning means having anvil lugs and clutch teeth formed thereon, a clutch member loosely spline connected to the shaft and having clutch teeth to engage the clutch teeth on the wrench turning means and the respective clutch asssfros teeth having cam faces for opening the clutch mechanism, a cylindricalhammer element revolvably fixed on the clutch member and having lugs on one end circumferentially disposed to "impact against the anvil lugs on the wrench turning means, a compression spring on the shaft for normally maintaining the clutch member with its clutch teeth in engagement with the wrench teeth thereby to rotate the wrench turning means, a torsion springl surrounding the compression vspring and having one end connected to the shaft and the other end connected to the hammer with the respective anvil and hammer lugs normally out of engagement thereby to form with the hammer .a torsion pendulum on the shaft and the angular spacing of the respective lugs and clutch teeth being such as to constitute an escapement mechanism to permit rebound pendulum action of the hammer relative to the camming action of clutch teeth.

10. In a' nutrunner, `a casing, a wrench turning means rotatably supported at anopen end of. the casing to extend therethrough,l a drive wrench` turning means and at its other end by a flexibly mounted power coupling means disposed ,'at--theopposite end of the casing, said wrench turning\means having anvil lugs and clutch teeth formed thereon, a clutch member loosely spline connected to the shaft and having clutch teeth `to engage the 'clutch teeth on the wrench turning means and the respective clutch teeth having cam faces for opening said clutch mechanism, a cylindrical hammer element revolvably fixed on the clutch member and having lugs on one end circumferentially disposed to impact against the anvil lugs on the wrench turning means, a compression spring on the shaft for normally maintaining the clutch member with its clutch teeth in' engagement with` the wrench teeth thereby 'to' rotate the wrench turning means, a torsion teeth to drivingly engage the clutchwteethfon shaft' rotatably supported at one end by the e the anvil member and the shapes of the anvil member andthe driving clutch teeth' being in the form of cams for effecting separation o'f'the respective clutch teeth when the driving clutch member is rotatedin either direction, acompression spring on the shaft for maintaining the respective clutch teeth in engagement to eif'ect rotation of the anvil member, an oscillatable hammer revolvably mounted upon and axially shiftable by the driving clutch member, said fhammer having impact lugs disposed to impact upon the anvil lugs, an unstressed pendulum torsion spring connected to the drive 'shaft and to the hammer in such manner that the impact lugs of the hammer andanvil member are out of spring surrounding the compression spring and 1 having vone end connected to the shaft in the region of the power coupling and the other end connected 'to the hammer with the respective anvil 'andliammer lugs normally out of engageme'nt'thereby to form a torsion pendulum and theangular spacing of the respective lugs and clutch teeth being such as to constitute an escapement mechanism to permit 'rebound pen- `dulum action of the hammer relative'to the camming action of the clutch teeth.

l1. In a tool of the character described, the combination of a casing, a shaft within the casing, a driving and a driven clutch member having camming teeth, one of the clutch members being "in the form of an anvil member supported by the casing and the other clutch member being 'loosely splined to the shaft for axial movement along the' shaft while being driven by the shaft,

a spring on the shaft yieldingly maintaining the clutch members engaged against the camming action of the clutch teeth, a hammer revolvably mounted upon the splined clutch member and having an impact shoulder adapted to strike an impact shoulder on the anvil clutch member and a normally unstressed pendulum torsion spring connecting the shaft and hammer with the impact lugs of the anvil and hammer angularly and l out of impact contact, the declutching camming -action being such that relative rotation between one of the clutchmembers and the hammer to accumulate energy in the torsion member by a contact during unarrested rotation of the anvil member and the spacing of the camming. Surfaces of the clutch teeth relative to the disposition of the hammer lugs is such that successive cammed escapements of the driving clutch mein'-v ber upon arresting of rotation the anvil mem ber" causes the rotative impis oi' the `hammer lugs upon the anvil lugs to b d up a successively increasing reverse motion. of the hammer and a vsuccessively increasing magnitude in the impact force delivered through the hammer lugs anvil lugs bythe pendulum spring.

. 13. In a nut runner of the portable type, a power driven shaft, wrench turning means,E a clutch mechanism connecting the shaft'n and wrench turning means, a spring on the shaft tothe -yieldably maintaining the clutch mechanism closed during a preliminary nut running operation, a cam means disposed between the -wrench turning means and an element of the clutch mechanism for overcoming the action of the spring -and for opening the clutch mechanism. a torsion pendulum oscillatable relative tothe clutch mechanism and having its center of ascii-'- lation on the shaftand arranged to deliver a series of tangential blows to the wrench turning means consequent to an intermittent yielding of the clutch mechanism, and stop means rotatable with the shaft and acting on the pendulum to limit the magnitude of angular displacement of the pendulum relative to the shaft.

GLENN c. WILHIDE.l

JAMES N. BAKER.

FRANK I.. HoLEoRD,

REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES. PATENTS Number Name Date 1,881,728 Lenedahl Oct. 11, 1932 1,954,620 Connell Apr. 10, 1934 2,061,843 Neumier Nov. 24, 1936 2,111,280 Connell Mar. 15, 1938 2,268,412 McCombs Dec. 30, 1941 

